Konkuri: web-based tournament organizer
Konkuri has a lot of features that are designed to make it not only easy to set up, but easy for people following or playing in your tournament to use. Dates, times and venues for matches are easy to enter and the results page does a lot of your work for you. When you enter results, Konkuri uses them to calculate standings. Depending on which sport you're playing, you can also enter scores from multiple sets in the same match (helpful for tennis, and the like). Each match also gets a comments page – what's a tournament site without the ability to talk trash?